On any version newer than 3.18.0 the LinuxCNC options under "Configuration" drop-down no longer work under CAM->CAM Legacy Export. As you can see in the attached screen shot, the menu line which would normally contain LinuxCNC is blank. Also, when LinuxCNC (Inch) and LinuxCNC (Millimeter) are selected, none of the Global or per-Layer options are available, it just says "No Global Options" and "No Layer Options" as you can also see in the screen shot. I think this is because both of these are derivatives of the main LinuxCNC configuration which is not working.

I have confirmed this problem with fresh installs (using the installer) on both Windows 10 and Debian testing